Improvement in let-off mechanism foe looms



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Letters Patent No. 72,987, datetlranuarg/ 7, 1868.` i i @its Srlgrbult return it in tlgrsie lettets atrnt :uit mating pai nf tige samt.

TO ALL PERSONS TO WHOMTHIESE PRESENTS MAY COME:

Be it known that I, GEORGE DRAPER, of Milford, in the county of Worcester, and State of Massachusetts,

have invented a new and useful or improved Let0ff Mechanismfor Looms for weavingcloth; anddo hereby declare thc same to be fully described in the following specification, and represented in the accompanying drawings, of which- Y Figure lis a top view, and

Figure 2 an end elevation' cfa loom-frame and lay with my said letofi` mechanism applied thereto.

Figure 3 is a vertical section, taken through the crank-shat`t, and representing the yarn-beam and such of the let-oil` mechanism as is in the immediate vicinity thereof.

In such drawings, 'A' denotes the loom-'frameg E, the lay; B', the crank-shaft for operating the lay; C is the yarn-beam or roller on which the warps arc wound.

The let-olf mechanism, to be hereinafter described, vis understood to operate in connection with what is usually termed a positive take-up motion or mechanism. Experience has demonstrated that cloth which requires much beat against the iilling or weft, usually requires the let-oi? mechanism to be so constructed that the tension of thc'warp, while the reed ofthe lay is against the cloth woven, cannot operate to increase the amount of yarn delivered, or prepare the loo'm to afterward deliver more in consequence of 'che increased pressure on the warps;- Experience hasalso proved that in weaving goods so thin that but little beat of the reed takes place, it is better to have the beat .to help deliver the warp ortopreparcfor its delivery when the reed may be next against the cloth. In lpoms for weaving thick goods, the delivery ofthe warp`s should be regulatedby the strain alone produced on the warps, and for those for weavingthin cloth, the delivery should be regulated by the beat and strain combined. When the delivery of the warp is governed by the beat of the lay and the tension ofthe warps, there will be less liability of production in the cloth of what Weavers term thick and thin places, but when the delivery ofthe warp is governed solely by the strain of the warp 'on the whiproller, the tension will be more equable, for the reason the delivery willnot take place during beat of the lay. Itis very desirable to adapt the loom to the production of either a thin or a thick fabric, and my' improved let-off mechanism, by a slight change or arrangement of one of its parts, will render the loom so applicable.

In carrying out my invention, I apply to one cf the journals a a, of the warp-guide B, an arm or lever, C, to extend down in rear oi' the ratchet-shaftF, in planner as represented in the drawings. This shaft F carries a ratchet, A, and engages with the yarn-beam by a pinion," b, and a spur-gear, c, the former being fixed on the inner end of the shaft F, and the gear cbcing fixed to the yarn-beam concentrically 'with its axis. Another arm, d, projecting from the' journal of the guide B, rests on the top of a helical spring, D, and is jointed to a v rod, c, which goes downv through tlfe spring, and a bracket,f, upon and by which lthe spring is supported. A

rocl erlevcr,.I, carrying on its upper end an impelling-pawl, K, is arranged alongside ofthe ratchet A, and has the shaft F for a fulcrum, the pawl K engaging with the ratchet. Furthermore, on the shaftF is a wheel, g, around which a friction-band, z., is carried, such band being fastened to the loom-frame. l To the lower arm of the lever I one end of a rod, Gr, is jointed, such rod, at or near its other end, being provided with a. slot, it', to v receive an arm, J, projecting from the sword of the lay.

The operation ofthe mechanism, when adapted for the production of thick goods by the loom, may be thus described: V l

When the lay E is fully forward, the warp which passes from the beam over and rests upon the warp-guide B, cannot depress the guide, because such guide will be held stationary by the arm or lever C, which will bear against the head of the joint-pin Il of the lever I, and rod G, the said pin H in turn beingheld stationary at 4such times by its connection with thelay through the rod Gr, and the arm J. Thus it will be seen that any amount of pressure or strain on the cloth cannot then change the position yof the pawl K. The beam at such time will be kept stationary by the friction-band and wheel hereinbefore mentioned: But when the crankshaft produces a recession of the lay, the arm .I will bc movedback in the slot L. vThis will leave the warp-guide B to be sustained by the helical spring I), which may be supposed to present a given amount of resistance to a depression of the guide B. Should the strain on the cloth caused by the taleup mechanism besuilciet to overcome this resistance of the spring, the warp-guideB will be depressed, and the lever C will be forced against the pin H, so as to move the lever I, and set back its pawl upon the ratchet. When the lay may next beat up, the arm J, by its draught on the rod G, will produce a movement of the lever I, lsuch as will cause the pawl thereof to turn the ratchet, and thus effect a slight `rotary motion of the yarn-beam, suflicient to eflect the requisite delivery of the warp. In case the strain on the warp may not be suilicient to overcome the resistance of the spring D, and set back the pawl upon the ratchet, no rotary motion ofthe said ratchet will be produced.

In order to adaptthe let-off mechanism to enable the loom to weave thin goodsrthe connecting-rod G should be removed Irom the pin H, and placed on a pin, z', at or near the upper end of the lever I. The operation of the parts of the let-oft` mechanism` will now be very different from that hereto explained. Commencing with the lay bach or at its furthest distance from the cloth, the pressure ofthe warp will be sustained by the spring D alone. The pawl K will be fully pressed back-.by the arm J', acting through the connecting-rod G. As the shaft may revolve, the lay will be pressed forward and the harnesses will open the warp. This, with the beat against the filling, and the action of the positive take-up motion, will produce an extra. strain upon the warp, which, if sufficient, will cause the warp-guide to be depressed, and will set back the catch on the wheel A as before mentioned. When the lay next goes back, it, through the connecting-rod G, will cause the wheel A to revolve as before mentioned. The same results might be produced by putting a cam on the loom-shaft, so as to operate the pawl-lever I instead of the arm on the lay and the connecting-rod G, but I nsider any such change a mere equivalent for the deviceor deviees-Ihave chosen to eie'ct like results.

From the above it will be seen that I have combined, with the warp-guide, the lay, and thcwarp-beam and its gearing, mechanism which will not only hold stationary the warp-guide at the beat of the lay, without allowing such beat to then produce delivery of the yarn, but will also allow the strain on the warp to operate directly upon and so as to turn a ratchet applied to the driving-shaft of such gearing. 'This mechanism consists of the spring D and the arms Z C, (applied to the loom-frame and the warp-guide 13,) thc friction-wheel and band,'the lever I, its pawl K, the arm J, and the rod G provided with a slot, 7L.

It will also be seen that in this mechanism I do not use any worm or bevelgears,isuch as are employed in the Bartlett and various other let-ofi` mechanisms for operating the yarn-beam of a loom, and which render them costly and complicated.

What, therefore; I claim as my invention, is

The said combination of devices, substantially a-s above described, for operating the said ratchet, the warpguide, and beam in manner as specified.

And furthermore, I claim their combination with the warp-'beam and its gearing, and ratchet, and with the warp-guide, and the lay,.the whole being substantially as explained..

GEORGE DRAPER..

Witnesses:

R. H. EDDY, F. I. HALE, Jr. 

